Tuning for cold air

[Holden202T]

yeah so that basically tells me its probably running in a part of the table that you haven't seen before so should be easily tunable, just a matter of getting it logged and adjusted.

[The1]

yeh and also having mods done will change things!

[charlay86]

Regular fuelling modes aren't affected by the air temp sensor, but Acceleration Enrichment has an air temp term which could be contributing to the increased fuel consumption

[immortality]

But AE would only be temporary so more fuel maybe on throttle movement but it shouldn't effect fueling otherwise?

[charlay86]

yes, correct, only on throttle increase. although the table may bot be calibrated to have much effect in a standard cal.
The colder the air your engine is breathing the more power it will make and obviously more air (colder air = denser air; n=PV/RT) needs more fuel.
It sounds like your CAI is working properly then. Maybe you need a HAI for cold weather fuel economy?
I remember my old alfa sprint had an exhaust "stove" to provide hot air to the air box in cold weather.

[vlad01]

My understanding is by having denser air, greater efficient can be had from a given engine, as long as the engine itself isn't cold due to the negative effects of the quench effect.

To me it sounds like the amount of fuel is excessive for the increase in volume, ie out of calibration.

No point in guess work, you need a wideband.

[charlay86]

the difficulty is that the PCM sees engine load increase with colder air (which is correct) but as the load is increased the AFR decreases etc. any table with cylinder air mass as an axis will be affected.

I'm not sure there is any simple way (ie calibration) around the issue, as we don't have an IAT AFR modifier

[vlad01]

how does it see a load increase? Wouldn't it see less due to less TPS? Load is how much the engine has to work to produce power, a more effect engine has lower load at a given output.

[charlay86]

MAF system uses Cylinder Air Mass as the load variable.
Denser air -> more load.
consider the open loop AFR table for instance, the axis are RPM and Cylinder Air Mass.
The TPS won't have any effect if the denser air pushes the CAM up and richens the AFR.

[immortality]

I guess we won't really know until we get some really cold weather again and I can get some datalogs of what is going on.

MY thinking as that if the engine is making X power to maintain cruise speed with warm air using Y throttle %age than changing to cooler air the engine would make more power so you would reduce the throttle %age to achieve the same power and cruise speed.

Wouldn't load be more a function of the TPS?